Design And Research On Archimedean Spiral Antenna With Wide-angle Coverage

In this paper, for requirements on high-gain, ultra-wideband, circularly polarized,wide-angle coverage, miniaturization and other features, an improved Archimedean spiralantenna was developed. The test results show that the antenna has good radiationcharacteristics all over the designing frequent band.On designing Archimedean spiral antenna, we optimize the number of the helical coiland minimize the diameter of the radiating body to reduce the non-circularity of the antennaradiation pattern. In order to achieve the characteristics of the wide angular coverage, wedeveloped an improved reflector cavity, hat-shaped cavity. By adding loadings at the end ofthe antenna, axial ratio can be improved and can be less than3dB all over the designingfrequent band. According to the impedance characteristics of the antenna, we designed anultra-wideband balun for this antenna. At the end of the paper, we also analyzed anddiscussed the asymmetry of the horizontal plane radiation.